Tool with end effector force limiter

Abstract

The invention provides surgical or diagnostic tools and associated methods that offer improved user control for operating remotely within regions of the body. In some embodiments these tools include a proximally-located actuator for the operation of a distal end effector, as well as proximally-located actuators for articulational and rotational movements of the end effector. Control mechanisms and methods refine operator control of end effector actuation and of these articulational and rotational movements. A force limiter mechanism protects the end effector and manipulated objects from the harm of potentially excessive force applied by the operator. The tool may also include other features. A multi-state ratchet for end effector actuation provides enablement-disablement options with tactile feedback. An articulation lock allows the fixing and releasing of both neutral and articulated configurations of the tool and of consequent placement of the end effector. A rotation lock provides for enablement and disablement of rotatability of the end effector.

What is claimed is: 
     
       1. A medical tool comprising:
 an end effector at a distal end of the tool; 
 an end effector actuator at a proximal end of the tool, the end effector actuator being operatively connected to the end effector through a linkage to deliver an actuation force from the end effector actuator to the end effector in response to movement of the end effector actuator, the linkage comprising an elongated actuation component defining an actuation axis; 
 a rod terminator coupled to the elongated actuation component; and 
 a force limitation assembly adapted to establish an upper limit on the actuation force delivered to the end effector by the end effector actuator, the force limitation assembly including an elongated force limiter component extending within and coupled to a force limiter housing, the force limitation assembly movably coupled to the end effector actuator and the force limiter housing removably coupled to the rod terminator,
 wherein when the actuation force delivered to the end effector actuator does not exceed the upper limit, the actuation force delivered to the end effector actuator causes linear movement of the elongated actuation component and the force limitation assembly along the actuation axis and 
 wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the linear movement of the elongated actuation component is terminated. 
 
 
     
     
       2. The medical tool of  claim 1  wherein when the actuation force exceeds the upper limit, movement of the end effector actuator causes at least a portion of the elongated actuation component to stretch. 
     
     
       3. The medical tool of  claim 2  wherein the at least a portion of the elongated actuation component is formed from a shape memory material. 
     
     
       4. The medical tool of  claim 1  wherein a portion of the elongated actuation component is held within the force limiter housing when the actuation force does not exceed the upper limit and separates from the force limiter housing when the actuation force exceeds the upper limit. 
     
     
       5. A medical tool comprising:
 an end effector at a distal end of the tool; 
 an end effector actuator at a proximal end of the tool, the end effector actuator being operatively connected to the end effector through a linkage to deliver an actuation force from the end effector actuator to the end effector in response to movement of the end effector actuator, the linkage comprising an elongated actuation component defining an actuation axis; and 
 a force limitation assembly adapted to establish an upper limit on the actuation force delivered to the end effector by the end effector actuator, the force limitation assembly movably coupled to the end effector actuator and removably coupled to the elongated actuation component,
 wherein when the actuation force delivered to the end effector actuator does not exceed the upper limit, the actuation force delivered to the end effector actuator causes linear movement of the elongated actuation component and the force limitation assembly along the actuation axis and 
 wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the linear movement of the elongated actuation component is terminated, 
 wherein the force limitation assembly includes an elongated force limiter component extending within a force limiter housing, and 
 wherein the elongated actuation component comprises a rod terminator including a channel sized to receive a distal end of the force limiter component and including a coupling portion sized to extend within the force limiter housing. 
 
 
     
     
       6. The medical tool of  claim 5  wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the coupling portion of the rod terminator separates from the force limiter housing. 
     
     
       7. The medical tool of  claim 5  wherein the force limiter component is coupled to the rod terminator pre-loaded with a predetermined stress. 
     
     
       8. The medical tool of  claim 1  wherein when the actuation force does not exceed the upper limit, the actuation force delivered to the end effector actuator causes sliding movement of the force limitation assembly along the actuation axis. 
     
     
       9. The medical tool of  claim 1  wherein the actuation force on the end effector actuator causes rotational movement of the end effector actuator about a pivot. 
     
     
       10. The medical tool of  claim 1  further comprising a movable slide member coupled to the force limitation assembly and slidable linearly along the actuation axis, wherein the end effector actuator includes a forked component that pivots with respect to the movable slide member when the actuation force is delivered to the end effector actuator. 
     
     
       11. The medical tool of  claim 1  wherein the end effector comprises a pair of jaws. 
     
     
       12. The medical tool of  claim 1 , wherein the rod terminator includes a channel sized to receive a distal end of the force limiter component and includes a coupling portion sized to extend within the force limiter housing. 
     
     
       13. The medical tool of  claim 12 , wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the coupling portion of the rod terminator separates from the force limiter housing. 
     
     
       14. The medical tool of  claim 1 , wherein the force limiter component is coupled to the rod terminator pre-loaded with a predetermined stress. 
     
     
       15. The medical tool of  claim 5 , wherein when the actuation force does not exceed the upper limit, the actuation force delivered to the end effector actuator causes sliding movement of the force limitation assembly along the actuation axis. 
     
     
       16. The medical tool of  claim 5 , wherein the actuation force on the end effector actuator causes rotational movement of the end effector actuator about a pivot. 
     
     
       17. The medical tool of  claim 5 , further comprising a movable slide member coupled to the force limitation assembly and slidable linearly along the actuation axis, wherein the end effector actuator includes a forked component that pivots with respect to the movable slide member when the actuation force is delivered to the end effector actuator. 
     
     
       18. The medical tool of  claim 5  wherein the end effector comprises a pair of jaws. 
     
     
       19. A medical tool comprising:
 an end effector at a distal end of the tool; 
 an end effector actuator at a proximal end of the tool, the end effector actuator being operatively connected to the end effector through a linkage to deliver an actuation force from the end effector actuator to the end effector in response to movement of the end effector actuator, the linkage comprising an elongated actuation component defining an actuation axis; 
 a force limitation assembly adapted to establish an upper limit on the actuation force delivered to the end effector by the end effector actuator, the force limitation assembly including an elongated force limiter component extending within and coupled to a force limiter housing, the force limitation assembly movably coupled to the end effector actuator and removably coupled to the rod terminator; and 
 a rod terminator coupled to the elongated actuation component and including a channel sized to receive a distal end of the force limiter component, the rod terminator removably coupled to the force limiter housing,
 wherein when the actuation force delivered to the end effector actuator does not exceed the upper limit, the actuation force delivered to the end effector actuator causes linear movement of the elongated actuation component and the force limitation assembly along the actuation axis and 
 wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the linear movement of the elongated actuation component is terminated. 
 
 
     
     
       20. The medical tool of  claim 19 , wherein when the actuation force delivered to the end effector actuator exceeds the upper limit, the rod terminator separates from the force limiter housing. 
     
     
       21. The medical tool of  claim 19 , wherein the force limiter component is coupled to the rod terminator pre-loaded with a predetermined stress. 
     
     
       22. The medical tool of  claim 19 , wherein when the actuation force does not exceed the upper limit, the actuation force delivered to the end effector actuator causes sliding movement of the force limitation assembly along the actuation axis. 
     
     
       23. The medical tool of  claim 19 , wherein the actuation force on the end effector actuator causes rotational movement of the end effector actuator about a pivot. 
     
     
       24. The medical tool of  claim 19 , further comprising a movable slide member coupled to the force limitation assembly and slidable linearly along the actuation axis, wherein the end effector actuator includes a forked component that pivots with respect to the movable slide member when the actuation force is delivered to the end effector actuator. 
     
     
       25. The medical tool of  claim 19 , wherein the end effector comprises a pair of jaws.